Ammunition reloader

ABSTRACT

Cartridge reloading apparatus of the type having a plurality of spaced stations where operations are performed on cartridges which move linearly and intermittently between stations under control of a shuttle bar. The shuttle bar is caused to move in a generally rectangular path to intermittently advance the cartridges. A cam pivots a crank arm connected to the shuttle bar to move the shuttle bar against the bias force of a spring to the advanced position. A second lobe on the cam restrains the return of the shuttle bar to the initial position to eliminate excessive noise and vibration. Locater holes are disposed in the shuttle bar and the base of the apparatus to periodically check the position of the shuttle bar relative to the work stations. A threaded shank carrying a roller bearing is provided to urge the shuttle bar into engagement with the cartridges but is easily removed to permit manual withdrawal of cartridges from the shuttle bar.

United States Patent Leich 51 July 25, 1972 [72] inventor:

s2 U.S.Cl ..86/26 51 .141: 11/02, F4lf 1 1/04 581 FieldotSear-ch ..86/26,25.23

[5 7] ABSTRACT Cartridge reloading apparatus of the type having a plurality of spaced stations where operations are performed on cartridges which move linearly and intermittently between stations under control of a shuttle bar. The shuttle bar is caused to move in a generally rectangular path to intermittently advance the cartridges. A cam pivots a crank arm connected to the shuttle bar to move the shuttle bar against the bias force of a spring to the advanced position. A second lobe on the cam restrains the return of the shuttle bar to the initial position to eliminate ex- [56] R f e Cit d cessive noise and vibration. Locater holes are disposed in the shuttle bar and the base of the apparatus to periodically check UNITED STATES PATENTS the position of the shuttle bar relative to the work stations. A 2,091.397 8/1937 Shockey threaded shank carrying a roller bearing is provided to urge 3,153,976 10/1964 Under "86/26 the shuttle bar into engagement with the cartridges but is easi- 3,036,488 5/1962 Bihler ..86/26 y removed to Permit manual withdrawal of cartridges from the shuttle bar.

Primary Examiner-Benjamin A. Borchelt Assistant Examiner-H. J. Tudor I Attorney-McGlynn, Reising, Milton & Ethington 19 Claims, 8 Drawing Figures mill'lllllll'l:

: Him 95 AMMUNITION RELOADER This invention relates to cartridge loading apparatus and specifically to such an apparatus in which cartridges are periodically cycled through a sequence of work stations by means of a shuttle bar.

Automatic cartridge loading devices are well known and it is customary in such devices to progress cartridges through a sequence of operations, each operation taking place at a different physical location in the apparatus. As an example, the loading of a previously used cartridge involves a shaping step, a cap removal step, a cap insertion step, powder metering, lead filling and crimping. All of these operations are carried out individually and individual locations and means are provided in an automatic machine for causing the cartridges to move between the stations in an intermittent fashion. From the foregoing it is apparent that the term cartridge loading as used herein refers not only to the original fabrication of ammunition including both bullets and shells, but also to the reloading of used or spent cartridges and casings for such bullets and shells.

In accordance with the invention, an automatic reloading apparatus comprises a base and shuttle bar on the base for moving cartridges between spaced stations where a sequence of operations is performed. The loading apparatus of the present invention includes drive means for cyclically displacing the shuttle bar in a predetermined path between an initial retracted position and an advanced position and means for precisely adjusting the position of the shuttle bar relative to the base in at least one of the positions to ensure that the shells are precisely located by the shuttle bar when the various operations are performed. This ensures that cartridges and shells will not be crushed, damaged, deformed, or improperly loaded during operation of the subject apparatus.

1 Another feature of the subject invention is the use of a double-lobe cam to provide not only positive displacement of the shuttle bar from the initial retracted position to the advanced position against the bias of a spring or other resilient device, but also for providing a controlled, gradual return of the shut tle bar to the initial retracted position, thus, to eliminate undue mechanical shock, vibration, and noise in the operation of the apparatus.

Another feature of the subject invention is the provision of means whereby the shuttle bar may be manually disengaged from the shells at any time without major disassembly of the apparatus. In general, this is accomplished by resiliently bias ing the shuttle bar into engagement with the cartridges, subject to normal cyclical travel thereof, by means of a roller which is disposed on a threaded shank which is, in turn, securedto the base for simple removal and, thus, relaxation of the bias force on the shuttle bar.

The subject invention provides further features and advantages such as the provision of a novel pusher arrangement to provide a generally rectangular path of shuttle bar travel as well as other such features which will become apparent upon reading of the following specification which describes a specific embodiment of the invention in detail. The specification is to be taken with the accompanying drawings of which:

FIG. 1 is a front view of a reloading apparatus embodying the invention,

FIG. 2 is a plan view along a section plane 2-2 of FIG. 1,

FIG. 3 is a partial plan view of the apparatus of FIG. 2 in a further advanced position,

FIG. 4 is a partial view of the apparatus of FIG. 2 showing the position thereof during the return movement of the shuttle bar,

FIG. 5 is a sectional view taken along the line 5-5 of FIG.

FIG. 6 is a sectional view of a detail taken along the section line 6--6 of FIG. 3,

FIG. 7 is a sectional view of a detail taken along a line 7-7 of FIG. 2, and,

FIG. 8 is a sectional view of a detail taken along the line 8- 8 of FIG. 2.

Referring now to FIGS. 1 and 2, there is shown an automatic cartridge reloader 10 of the type used to perform a sequence of operation to effect the automatic reloading of spent cartridges. The reloader 10 illustrated is designed to reload 38 caliber bullets, but other types of ammunition, including shotgun shells, can be accommodated with a few obvious modifications. Apparatus 10 comprises a heavy base 12, preferably steel, carrying a pair of spaced vertical guide pins 14 which support for vertical reciprocation a platen assembly 18. Platen assembly 18 carries, as best shown in FIG. 1, a plurality of evenly spaced, cylindrical work station dies 19, the righthandmost die being in vertical registration with discharge chute 21. Dies 19 are lowered into surrounding relationship with cartridges moving along the horizontal surface of base 12 under the control of a shuttle bar 20 having a plurality of evenly spaced slots 22 for engagement with the generally upright cartridges (not shown). Shuttle bar 20 is maintained on base 12 by a cover plate 24, which is bolted to base 12.

Shuttle bar 20 is caused to move through a substantially rectangular path between an initial retracted position generally shown in FIG. 2 wherein the cartridges are engaged by the shuttle bar and an advanced position wherein the shuttle bar 20 and the cartridges are moved in unison to the right, as shown in FIGS. 3 and 4 such that the cartridges are placed in position for the performance of the next operation thereon. Once the shuttle bar 20 has reached the advance position, it is caused by means to be described to move forwardly (downwardly in FIG. 2) to disengage the slots 22 from the cartridges. In this position the shuttle bar 20 may be moved back to the left toward the initial retracted position without interfering with the cartridges on the horizontal surface of base 12. Shuttle bar 20 is then permitted by means to be described to move rearwardly (upwardly in FIG. 2) into engagement with the cartridges, the cycle then repeating over and over again as long as the apparatus 10 is in operation. Shells are preferably fed constantly and continuously to the apparatus by suitable means associated with tube 104.

The lateral movement of the shuttle bar 20 is controlled by drive means including a crank arm 26 which is connected to the base 12 for pivotal movement about an axis of rotation generally coextensive with hollow pivot tube 28 in FIG. 2. The free end of crank arm 26 has formed therein a deep slot 30 which slidingly cooperates with a roller arrangement 32 on an upstanding pin carried at the left end of the shuttle bar 20 as seen in FIG. 2. The retracted position of shuttle bar 20 is defined by the position of limit stop means 34 carried on base 12 and engaging the crank arm 26. The limit stop means 34 is adjustable by means of a threaded connection as indicated. The advanced position of shuttle bar 20 is determined by the location of a slide bar 36 which is carried by an adjustable carriage 37 on base 12 and a rectangular slot 38 in the righthand end of the shuttle bar 20 again as shown in FIG. 2, 3, and 4.

The drive means for causing displacement of the shuttle bar 22 further comprises a motor driven shaft 40 which is disposed through the center of the base 12 and which carries a cam 42 which cooperates with a roller 44 on the end of a lever arm 46 which is in turn rigidly connected to the crank arm 26 of FIG. 2. A heavy coil spring 48 is disposed about the pivot shaft between the crank arm 26 and the lever arm 46 and securred to base 12 as shown in FIG. 5, to bias the crank arm 26 and, thus, the shuttle bar 20 to the initial retracted position. Cam 42 has a first lobe 50 which, when the cam is rotated by suitably driving the shaft 40, causes the lever arm 46 and roller 44 to move in a counterclockwise path in the view of FIG. 2 to in turn cause the free end of the crank arm 26 to move from left to right advancing the shuttle bar 20 toward the right as shown in FIG. 2. Cam 42 further comprises a second lobe 52 which is spaced from lobe 50 by means of an intermediate valley section to constrain the return of the shuttle bar 20 to the initial position against the bias of spring 48.

Shuttle bar 20 is urged against a laterally extending and rearwardly spaced guide rail 54 which is secured to the base 12 by means .of machine screws, as shown. The fore-and-aft bias on shuttle bar is produced by a spring-loaded roller 56 containing a plurality of needle bearings for rotation about an upright pin 58. The pin 58 is carried on the inner end of a stub shaft 60 which is telescopically engaged with a hollow, cylindrical plunger 62. Plunger 62 has a threaded portion 64, best shown in FIG. 8, which engages with the correspondingly threaded horizontally extending hole in the base 12. The hollow plunger 62 contains a spring 66 which on the free end engages the stub shaft 60 to bias the roller 56 against the forward vertical edge of the shuttle bar 20. The plunger 62 is easily removed from the base 12 to relax tension on the pin 58 and, thus, on the shuttle bar 20 simply by unscrewing it from the tapped hole. Thus, the shuttle bar 20 may be withdrawn forwardly from engagement with the cartridges in the slots 22 without removing the overlying plate 24 which holds the shuttle bar 20 in position on the base 12. Plate 24 is suitably provided with a slot 68 which provides fore-and-aft clearance for the roller 56 as best shown in FIGS. 2 and 8.

In summary, the shuttle bar .20 which controls the move- 7 ment of cartridges between the dies 19 of platen assembly 18 or, more accurately, the projections of dies 19 on the horizontal surface of base 12 is biased by spring 48 operating on crank arm 26 to the retracted'lateral position and is biased into engagement with the cartridges as well as the rail 54 by means of spring 66 and the plunger 62; therefore, when crank arm 26 is rotated in the counterclockwise direction by lobe 50 of cam 42 to advance the shuttle bar 20, it is necessary to urge the shuttle bar 20 away from rail 54 and away from the cartridges before it can be returned from right to left, that is, from the advanced position to the initial retracted position, without interference with the cartridges.

The means for urging the shuttle bar 20 away from plate 54 includes pusher bars 70 and 72 which are disposed in foreand-aft slide housings 74 and 76 on the base 12. Pusher bar 72, for example, is shown in FIG. 7 to be provided with a beveled end surface 78 which cooperates with the beveled end surface 80 of a pin 82 depending vertically from platen assembly 18. A similar depending pin 84 cooperates with the pusher bar 70, as shown in FIG. 2. Pusher bars 70 and 72 are biased by springs 86 and 88 to a retracted position wherein they are disengaged from the shuttle bar 20 but are urged toward the shuttle bar 20 by the downward motion of the platen assembly 18.

As shown in FIGS. 3 and 4, the pushers 70 and 72 engage the rearward vertical edge of the shuttle bar 20 to push it away from the guide rail 54 so as to be clear of the cartridges for the return to the retracted position. As suggested in FIG. 7, a vertical portion of the pin 82 provides a dwell of the pusher bars 70 and 72 in the extended position around the bottom dead center position of the cyclically moving platen assembly 18. For the details of a suitable connection for providing the vertical reciprocating motion of the platen assembly 18, reference should be taken to the Applicant's U.S. Pat. No. 3,580,128.

As indicated in FIG. 5, the indexing lobe 50 which produces the displacement of the shuttle bar 20 from the initial to advanced position is spaced from the return lobe 52 and preferably causes the shuttle bar 20 to slightly overrun the advanced position in which the cartridge-loading operations are to take place. During this forward travel, the beveled surface 90 of the shuttle bar 20 causes retraction of the slide bar 36 against the bias of spring 92, as shown in FIGS, 2, 3, and 4. The slide bar 36 is fully retracted and the spring 92 fully extended in the position illustrated in FIG. 3. The carn lobe 50 is such that shuttle bar 20 continues to move to the right in view of FIG. 3 until the spring biased slide bar 36 is permitted to fall into the slot 38 previously occupied by the pusher bar 72. At this point the lobe 50 clears the roller 44 and pemiits the shuttle bar 20 to fall back into engagement with the slide bar 36 which now extends into the slot 38. Slide bar 36 thus prevents the further movement of shuttle bar 20. It is in this position that the platen assembly 18 reaches the bottom dead-center position and the cartridge reloading operations take place.

From the foregoing it can be seen that the location of the slide bar 36 relative to the base 12 is of critical importance in that this relative position determines the position of shuttle bar 20 at which the cartridge reloading operations take place. Moreover, the position of shuttle bar 20 determines the position of the cartridges relative to the dies 19 which define the various stations. Accordingly, should slide bar 36 be laterally out of position, the shuttle bar 20 and the cartridges which are moved thereby will also be out of position and may be crushed by the descending motion of the platen assembly 18. To provide for proper alignment of the slide bar 36 relative to base 12, carriage 37 is made adjustable by means of set screws 94 and 96 which permit the entire assembly to be rapidly adjusted relative to the base 12. A convenient mechanism for determining whether an adjustment is required involves the precise drilling of a locater hole 98 in the right-hand end of the shuttle bar 20 as best shown in FIG. 2 and the drilling of a locater hole 100 in the base 12, as also shown in FIG. 2. The locater holes 98 and 100 are so disposed that when the shuttle bar 20 is placed in the proper position for cartridge-loading operations by the slide bar 36, it is possible to readily insert a pin 102 into the aligned combination of holes 98 and 100, as best shown in FIG. 6. If it is not possible to insert the pin 102 alignment is necessary by adjustment of the carriage 37 relative to the base 12.

OPERATION The operation of the apparatus 10 will now be described by reference to a typical cartridge-loading operation.

Empty cartridges are continuously fed, base down, to the horizontal surface of base 12 by means of a cartridge supply tube 104. The cartridges fall onto the base 12 in such a position that the lefthandmost slot 22 in the shuttle bar 20 moves into surrounding engagement with the cartridge urging it against the rail 54. Shaft 40 is rotated by means of a suitable electric motor to bring cam lobe 50 into engagement with roller 44 rotating lever arm 46 and crank arm 26 in the counterclockwise direction about the pivot point 28. This rotation causes the shuttle bar 20 to be moved from left to right as shown in FIG. 2 advancing the cartridges from the lefthandmost station of FIG. 1 to the next station where the next operation takes place. This advance from left to right occurs while the platen assembly 18 is in a raised position relative to base 12. Thus, the pins 82 and 84 do not engage the pusher bars and 72 and the springs 86 and 88 cause the pusher bars to be retracted rearwardly out of engagement with the shuttle bar 20. As the shuttle bar 20 moves to the right, as shown in FIG. 2, the tapered-leading surface causes retraction of the slide bar 36 permitting the slide bar to slide over the flat surface between the beveled surface 90 and the slot 38. Once reaching the slot 38, the slide bar 36 falls into the slot such that the movement of the indexing lobe 50 away from the roller 44 does not permit the shuttle bar 20 to return to the left, but keeps it locked in position by the interaction between slide bar 36 and slot 38. At this time the platen assembly 18 descends such that the dies 19 occupy a surrounding relationship to the upstanding cartridges.

As the platen assembly descends, the pins 82 and 84 come into engagement with the beveled end surfaces of the pusher bars 72 and 70, respectively, as best shown in FIG. 7 to urge the shuttle bar 20 forwardly away from rail 54. The cartridges are held in position by the dies 19 and, thus, are unaffected by the disengagement of the shuttle bar 20. The extension of the pusher bars 70 and 72 urges the shuttle bar 20 away from the rail 54 and away from the carriage 37 such that ultimately the slide bar 36 is drawn out of the slot 38. At this point the clock spring 48 on the crank arm 26 urges the shuttle bar 20 back toward the initial retracted position but the mechanical shock, noise, and vibration which would be accompanied by a complete, unrestricted return is prevented by means of the return lobe 52 on the cam 42. Lobe 52 picks up the roller 44 and constrains the return motion of shuttle bar 52 to a gentle, controlled motion.

During the return of the shuttle bar 20 to the retracted position, the platen assembly 18 passes the bottom dead-center position and begins to ascend. However, while in the lowermost position, the pusher bars 70 and 72 are nevertheless extended as shown in FIG. 2. Thus, when the shuttle bar 20 returns to the retracted position defined by the limit stop means 34, the slot 38 on the righthand side and the corresponding slot 106 on the left-hand side of the shuttle bar 20 provide clearance for the pusher bars 70 and 72 and permit the shuttle bar 20 to return into engagement with the plate 54 notwithstanding the extended position of the pusher bars. The spring bias to return the shuttle bar 20 into engagement with plate 54 is, of course, provided by spring 66 and the plunger 62.

Periodically, one inserts the pin 102 through the aligned holes 98 and 100 in the shuttle bar and base, respectively. If the pin 102 does not readily go in, one stops the operation of the machine and adjusts the position of the carriage 37 relative to the base 12.

Should a cartridge become damaged or otherwise cause the machine to malfunction, the machine may be stopped and the offending cartridge may be simply removed by removing the plunger 62 from engagement with the base 12 and manually pulling the shuttle bar 20 away from the rail 54. The removal of plunger 62 relaxes the bias on the shuttle bar and permits it to be easily withdrawn from the position shown in FIG. 2.

It is to be understood that the embodiment of the drawings and described above is illustrative of the invention and is not to be construed in a limiting sense.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a cartridge loading apparatus having a plurality of laterally spaced stations where a sequence of operations are performed on the cartridges: a base; a shuttle bar laterally slidably disposed on the base for moving the cartridges between the stations; drive means for cyclically laterally displacing the shuttle bar in a predetermined path between laterally advanced and laterally retracted positions; and means independent of said drive means for readily efl'ecting minor adjustments in the lateral position of the bar relative to the base in at least one of the positions, the last-mentioned means including a position reference on the base for indicating the desired relative position of the bar when in said one position.

2. Apparatus as defined in claim 1 wherein said drive means includes a crank arm pivotally mounted on the base and engaging the shuttle bar, and means for cyclically pivoting the crank arm.

3. Apparatus as defined in claim 2 including a spring for biasing the crank arm and the shuttle bar to the retracted position.

4. Apparatus as defined in claim 3 including limit stop means on the base and operatively engageable with the crank arm to define the retracted position.

5. Apparatus as defined in claim 2 wherein the means for cyclically pivoting includes a rotatable drive shaft and a cam on the shaft, said cam being operative to pivot the crank arm.

6. Apparatus as defined in claim 5 wherein the cam includes a first lobe for causing the shuttle bar to move to the advanced position and a second lobe for gradually permitting the shuttle bar to return to the retracted position.

7. Apparatus as defined in claim 6 wherein the two cam lobes are spaced apart to permit the shuttle bar to dwell in the advanced position during continuous rotation of the cam.

8. Apparatus as defined in claim 1 wherein said predetermined path is substantially rectangular in configuration such that the shuttle bar is drawn out of engagement with the cartridges during the movement from the advanced to the retracted positions.

9. Apparatus as defined in claim 8 including pusher means on the base for periodically urging the shuttle bar away from the cartridges.

10. Apparatus as defined in claim 9 wherein the pusher means includes a pair of spaced pusher bars, means for biasing the bars to a disengaged position and cycling means for engaging the pushers with e shut e bar at the advanced posi tion thereof.

11. Apparatus as defined in claim 10 including upright support means on the base, a vertically reciprocal assembly on the support means, the cycling means including a pair of pins depending from the assembly and having bevelled end surfaces engageable with the ends of the pusher bars.

12. Apparatus as defined in claim 8 including means positively engageable with the shuttle bar for holding the shuttle bar in the advanced position.

13. Apparatus as defined in claim 12 wherein the holding means includes a rigid slide bar displaceable toward and away from the shuttle bar, a slot in the shuttle bar for receiving the slide bar when the shuttle bar is in the advanced position and means biasing the slide bar into the slot.

14. Apparatus as defined in claim 10 including a pair of spaced notches in the shuttle bar for receiving the pusher bars when the shuttle bar is in the retracted position.

15. Apparatus as defined in claim 12 wherein the means for adjusting is disposed between the holding means and the base.

16, Apparatus as defined in claim 15 including locater holes in the shuttle bar and base in such location and orientation as to be aligned when the shuttle bar and holding means cooperate in the advanced position.

17. Apparatus as defined in claim 9 including bias means on the base for urging the shuttle bar into engagement with the cartridges.

18. Apparatus as defined in claim 17 wherein the bias means includes a needle bearing roller engageable with an edge of the shuttle bar and a threaded shank for holding the roller to the base, the roller and shank being disengageable to permit the shank to be withdrawn from the base.

19. Cartridge loading apparatus including a base, a shuttle bar on the base for moving cartridges between spaced stations, means for moving the shuttle bar cyclically between advanced and retracted posifions, said means including a cam having a first lobe for urging the shuttle bar toward the advanced position and a second lobe for restraining the return of the shuttle bar to the retracted position according to rotation thereof. 

1. In a cartridge loading apparatus having a plurality of laterally spaced stations where a sequence of operations are performed on the cartridges: a base; a shuttle bar laterally slidably disposed on the base for moving the cartridges between the stations; drive means for cyclically laterally displacing the shuttle bar in a predetermined path between laterally advanced and laterally retracted positions; and means independent of said drive means for readily effecting minor adjustments in the lateral position of the bar relative to the base in at least one of the positions, the last-mentioned means including a position reference on the base for indicating the desired relative position of the bar when in said one position.
 2. Apparatus as defined in claim 1 wherein said drive means includes a crank arm pivotally mounted on the base and engaging the shuttle bar, and means for cyclically pivoting the crank arm.
 3. Apparatus as defined in claim 2 including a spring for biasing the crank arm and the shuttle bar to the retracted position.
 4. Apparatus as defined in claim 3 including limit stop means on the base and operatively engageable with the crank arm to define the retracted position.
 5. Apparatus as defined in claim 2 wherein the means for cyclically pivoting includes a rotatable drive shaft and a cam on the shaft, said cam being operative to pivot the crank arm.
 6. Apparatus as defined in claim 5 wherein the cam includes a first lobe for causing the shuttle bar to move to the advanced position and a second lobe for gradually permitting the shuttle bar to return to the retracted position.
 7. Apparatus as defined in claim 6 wherein the two cam lobes are spaced apart to permit the shuttle bar to dwell in the advanced position during continuous rotation of the cam.
 8. Apparatus as defined in claim 1 wherein said predetermined path is substantially rectangular in configuration such that the shuttle bar is drawn out of engagement with the cartridges during the movement from the advanced to the retracted positions.
 9. Apparatus as defined in claim 8 including pusher means on the base for periodically urging the shuttle bar away from the cartridges.
 10. Apparatus as defined in claim 9 wherein the pusher means includes a pair of spaced pusher bars, means for biasing the bars to a disengaged position, and cycling means for engaging the pushers with the shuttle bar at the advanced position thereof.
 11. Apparatus as defined in claim 10 including upright support means on the base, a vertically reciprocal assembly on the support means, the cycling means including a pair of pins depending from the assembly and having bevelled end surfaces engageable with the ends of the pusher bars.
 12. Apparatus as defined in claim 8 including means positively engageable with the shuttle bar for holding the shuttle bar in the advanced position.
 13. Apparatus as defined in claim 12 wherein the holding means includes a rigid slide bar displaceable toward and away from the shuttle bar, a slot in the shuttle bar for receiving the slide bar when the shuttle bar is in the advanced position and means biasing the slide bar into the slot.
 14. Apparatus as defined in claim 10 including a pair of spaced notches in the shuttle bar for receiving the pusher bars when the shuttle bar is in the retracted position.
 15. Apparatus as defined in claim 12 wherein the means for adjusting is disposed between the holding means and the base.
 16. Apparatus as defined in claim 15 including locater holes in the shuttle bar and base in such location and orientation as to be aligned when the shuttle bar and holding means cooperate in the advanced position.
 17. Apparatus as defined in claim 9 including bias means on the base for urging the shuttle bar into engagement with the cartridges.
 18. Apparatus as defined in claim 17 wherein the bias means includes a needle bearing roller engageable with an edge of the shuttle bar and a threaded shank for holding the roller to the base, the roller and shank being disengageable to permit the shank to be withdrawn from the base.
 19. Cartridge loading apparatus including a base, a shuttle bar on the base for moving cartridges between spaced stations, means for moving the shuttle bar cyclically between advanced and retracted positions, said means including a cam having a first lobe for urging the shuttle bar toward the advanced position and a second lobe for restraining the return of the shuttle bar to the retracted position according to rotation thereof. 